Had new fuel injectors, tune-up, all vacuum lines repaired etc.......

Truck ran like a top when I picked it up from the shop, 10 minutes later at a red-light it started sputtering. Took it back and picked it up again today. Once again it played out exactly like it did before, stopped at a red-light and it started sputtering again. Both the mechanic and myself are very puzzled as to what could be causing this problem.

Any help is greatly appreciated